Sex on Six Legs by Marlene Zuk

Source of book: My wife found this on the library discards shelf, so we decided to get it as a gift for an insect-loving person we know. But I obviously had to read it first. 

This was clearly one of this “hey, provocative title so a perfect gift for the right person.” But actually, I really enjoyed this book, which is both well researched and well written. 

Marlene Zuk isn’t primarily a writer. Her main job is a researcher and college professor, currently at the University of Minnesota, having worked previously for the University of California, Riverside. Her main areas of research have been sexual selection, and parasites. Which, well, seriously fascinating stuff as far as I am concerned, although I find to my disappointment that not everyone shares my taste.

How did I come to love bugs so much? I’m not really sure, but I do recall that the 1968 classic, Insects do the Strangest Things, was one of my favorite books as a small child. I recall devouring other books along that line from the library too. I like creepy crawlies, shall we say. 

Sex on Six Legs doesn’t quite fit its salacious title. Not even half of the chapters are about sex in the sense of mating. Rather, they look at genetics, evolution, and insect behavior in general. So, such things as insect language (think hymenoptera and termites), insect parenting, the ability of arthropods to learn, the balance of male and female in populations, and other such interesting topics find their way into this book. 

And yes, sex is one of the topics. After all, reproduction is one of the necessary traits of life, and the innate drive to perpetuate our DNA is one of the most interesting areas of study for an evolutionary biologist. This is particularly the case for insects because, unlike, say, humans, the life cycle of six-legged creatures is short, making experiments far more practical. (Not so much, perhaps, as bacteria, but insects also are closer to humans than bacteria - an uncomfortable truth that Zuk brings up regularly throughout the book.) 

One of the things that surprised me most about the book was that Zuk is an excellent and compelling writer. More often in my experience, I have found that good writers can learn enough of the science to put together an enjoyable, informative, and accurate book - but researchers often struggle to make their areas of expertise come alive. Thus, many of my favorite PopSci writers are primarily writers: Mary Roach, Sam Kean, Simon Winchester. There are, of course, some exceptions. Phillip Plait comes to mind. I am definitely adding Zuk to the list. She has written three other books, two of which are available from our library system. I am definitely adding them to my reading list. 

One of the most fascinating facts that Zuk points out is this: because insects are such an ancient life form, they have a tremendous amount of genetic diversity. Which leads to an equally astounding diversity in form, behavior, and gene differences. As Zuk notes, an elephant and a mouse are far more alike than a grasshopper and a flea. Even such things as the total amount of DNA in the cell varies far more among insects than vertebrates. 

And then, there is the subcategory of beetles. Fully one quarter of ALL the known species of animals are beetles. There are an astonishing 350,000 plus known species, with vast differences in diet, size, habitat, and behavior. 

Zuk spends a good bit of time discussing genes - unsurprising given her research on the subject. She also does a great job of explaining how specific genes work. (It doesn’t hurt to have some prior knowledge, though. I recommend Herding Hemingway’s Cats by Kat Arney for an excellent and thorough overview of modern genetics. And Sam Kean’s The Violinist’s Thumb for a more story-based approach.) 

There were a number of moments when I found Zuk’s specific pet peeves to be very like my own. For example, she opens chapter 4 with a fine whine about the way that Hollywood seems to prefer to portray social insects (bees and ants in particular) as male. Which is utter bullcrap. Yes, there are male bees and ants. We call them “drones,” and they are useless for anything other than sperm, and have no role in the complex insect societies. So, Jerry Seinfeld as a “worker bee” is just….wrong. And particularly so since the fact that most hymenoptera are female has been known for literally hundreds of years. Besides, as Zuk emphasizes, the truth is much more fascinating. Males come from unfertilized eggs - and have half the DNA of females. Thus, daughter females share 75% of their DNA with each other, but only 25% with their drone brothers. This leads to some...interesting genetic payoffs. It’s too complicated to explain here, but seriously, read the book. 

Actually, the whole discussion of sex ratios was crazy. Although the effect is less in first world nations, because there is less malnutrition, women who are better nourished tend (at the population level) to produce more male children, while those less nourished tend to produce more female children. This is predictable, given the specifics of human mating: because females are the limiting factor in reproductive rates, they are likely to be in demand even if less healthy. Whereas males, who can reproduce nearly infinitely, compete with each other. (Obviously, this is less apparent in a complex society, but the genetic realities stem from our evolutionary past. Monogamy is, to put it mildly, a startlingly modern idea in our species.) 

Also fascinating was the chapter that focused on homosexual behavior in insects. This area of study has been fraught with controversy, not least because it challenges religious beliefs. As with other facets of animal behavior, it is easier to be (closer to) objective with insects, as we are less likely to project our own interpretations on them than we are on mammals. Although (as the book points out), insects are not automatons, they also do not seem to have “emotions” as we understand them. And certainly, they do not “sin” - what they do is largely the result of genetic programming, not individual choice. And thus, discovering “deviant” behavior in insects can be an aid in rethinking what we think we know about ourselves as well.

Another nice moment was when Zuk riffed briefly on “cyberchondria,” the tendency to look up dire diagnoses online at the first sign of a sniffle. She uses this to introduce the concept of “fertilization myopia,” considering coitus as the end of the story. Which it isn’t, even in the insect world. In fact, a whole bunch of interesting physiological and behavioral adaptations have arisen to affect which sperm successfully reproduces. This ranges from males being able to displace the sperm of previous males, to females being able to select which sperm is used. 

Perhaps the most startling fact from this section (and that is saying A LOT - this whole subject is nuts...pardon the pun) is the discussion of sperm size. Humans, for what it is worth, have relatively small and boring sperm. It gets the job done, but that’s about it. Now, on the other hand, one of the species of fruit fly (which are ubiquitous in this book because they are so often studied) has sperm which is...wait for it...twenty times the length of the male producing it. Say what!??! If that were expanded to human size, we guys would have sperm cells 100 or more feet long. As I said, rather crazy. 

There are so many additional bits to this book that were thoroughly enjoyable and informative. The discussion on what makes for a “language” is thoughtful and a bit disturbing: much of what we have decided makes us “human” can be found, at least in part, in those primitive six legged creatures. 

And this leads to my closing thought. In the last two pages of the book, Zuk transitions from insect language to poetry. Specifically, the poetry of Don Marquis, the creator of archie and mehitabel, the unforgettable cockroach and cat duo. 

What’s that? You haven’t heard of them? 

What IS this world coming to?

Writing during the Jazz Age, Marquis put together humor and biting social commentary using the idea of a cockroach with the soul of a poet devotedly typing his thoughts by jumping on the keys of a typewriter. (He can’t hold down the shift key, so everything is in lowercase.) 

I was, to say the least, thrilled to see that Zuk is a fellow aficionado of Marquis. She goes so far as to quote a couple of passages about the contrast - and similarities - between insects and humans. Although written about 100 years ago in some cases, these poems seem strikingly relevant and modern. Zuk quotes just a sanza of “what the ants are saying.” Here is the whole thing:

dear boss i was talking with an ant

the other day

and he handed me a lot of

gossip which ants the world around

are chewing over among themselves

i pass it on to you

in the hope that you may relay it to other

human beings and hurt their feelings with it

no insect likes human beings

and if you think you can see why

the only reason i tolerate you is because

you seem less human to me than most of them

here is what the ants are saying

it wont be long now it wont be long

man is making deserts of the earth

it wont be long now

before man will have used it up

so that nothing but ants

and centipedes and scorpions

can find a living on it

man has oppressed us for a million years

but he goes on steadily

cutting the ground from under

his own feet making deserts deserts deserts

we ants remember

and have it all recorded

in our tribal lore

when gobi was a paradise

swarming with men and rich

in human prosperity

it is a desert now and the home

of scorpions ants and centipedes

what man calls civilization

always results in deserts

man is never on the square

he uses up the fat and greenery of the earth

each generation wastes a little more

of the future with greed and lust for riches

north africa was once a garden spot

and then came carthage and rome

and despoiled the storehouse

and now you have sahara

sahara ants and centipedes

toltecs and aztecs had a mighty

civilization on this continent

but they robbed the soil and wasted nature

and now you have deserts scorpions ants and centipedes

and the deserts of the near east

followed egypt and babylon and assyria

and persia and rome and the turk

the ant is the inheritor of tamerlane

and the scorpion succeeds the caesars

america was once a paradise

of timberland and stream

but it is dying because of the greed

and money lust of a thousand little kings

who slashed the timber all to hell

and would not be controlled

and changed the climate

and stole the rainfall from posterity

and it wont be long now

it wont be long

till everything is desert

from the alleghenies to the rockies

the deserts are coming

the deserts are spreading

the springs and streams are drying up

one day the mississippi itself

will be a bed of sand

ants and scorpions and centipedes

shall inherit the earth

men talk of money and industry

of hard times and recoveries

of finance and economics

but the ants wait and the scorpions wait

for while men talk they are making deserts all the time

getting the world ready for the conquering ant

drought and erosion and desert

because men cannot learn

rainfall passing off in flood and freshet

and carrying good soil with it

because there are no longer forests

to withhold the water in the

billion meticulations of the roots

it wont be long now It won’t be long

till earth is barren as the moon

and sapless as a mumbled bone

dear boss i relay this information

without any fear that humanity

will take warning and reform

And this bit, from the collection I reviewed nearly seven years ago:

i do not see why men

should be so proud

insects have the more

ancient lineage

according to the scientists

insects were insects

when man was only

a burbling whatisit

I am looking forward to reading other books by Zuk. This one is worth seeking out. In fact, here is another poem by archy that seems to fit. (It’s my favorite…) 

there are two

kinds of human

beings in the world

so my observation

has told me

namely and to wit

as follows

firstly

those who

even though they

were to reveal

the secret of the universe

to you would fail

to impress you

with any sense

of the importance

of the news

and secondly

those who could

communicate to you

that they had

just purchased

ten cents worth

of paper napkins

and make you

thrill and vibrate

with the intelligence

                   archy

Marlene Zuk is definitely one of the second type.